1. Field of the Invention
The present invention relates generally to apparatus utilizing cryogenic material to brand the hide of a live animal.
2. Description of the Prior Art
The branding of animals has traditionally been effected by means of a hot branding iron applied to the hide of an animal to burn off the hair and also burn the skin so as to form scar tissue in which the hair does not grow back. This method of branding was painful to the animal, produced a mild trauma on the skin which is open to infection and is a time consuming and distasteful job for the persons required to do the branding.
A more contemporary approach to branding uses a cryogenic material to kill the pigment producing cells (melanocytes) of the hair. The hair in the exposed area will then grow out white to result in a permanent marking.
Freezing an area of animal hide is accomplished by either supercooling a branding iron to be brought into contact with the animal hide or by applying the cryogenic material directly to the hide of the animal.
Hogg U.S. Pat. No. 3,515,096, granted Mar. 18, 1968, Berens U.S. Pat. No. 3,358,648, granted May 26, 1967, and Drayson U.S. Pat. No. 3,568,464, granted Mar. 10, 1969, are apparatus which utilize cryogenic material to cool a branding iron to a selected subfreezing temperature which is then pressed firmly against the hide of an animal to effect local controlled freezing of an area corresponding to the shape of the branding iron. As described above, there is a subsequent regrowth of white hair in the shape of the brand design.
One disadvantage inherent in these type of apparatus is that the hair of the animal frequently acts as an insulator by preventing adequate contact between branding iron and the hide with inadequate depigmentation of the dark hair follicles resulting. Because of this, it is frequently necessary to shave the hair off the hide of the animal in order for the branding iron to be effective. Another disadvantage is that an unduly long period of time is required for the branding iron to cool to a sufficiently low temperature level, and the iron must also be recooled after each application of the brand. If the branding iron becomes warm before the animal is adequately branded, a second application of the iron may be necessary, which leads to problems to registration between the first and second brands. However, if the branding iron is applied to the animals hide too long, it may cause permanent removal of the hair as well as open sores and/or wounds. A further disadvantage is that a multitude of branding iron heads or insignia are necessary if a unique brand on each animal is desired.
The other method utilizing cryogenic material to brand the hide of an animal is to apply the cryogenic material directly to the hide of the animal. Farrel U.S. Pat. No. 3,362,381, granted Jan. 9, 1968 generally indicates a method for applying a cryogenic material directly to the hide of an animal, but it fails to disclose any apparatus for accomplishing this.
The direct application of a cryogenic gas to the hide of a live animal is disclosed by Canoy U.S. Pat. No. 3,411,483, granted Dec. 19, 1966. Because gaseous cryogenic material frequently cannot be cooled sufficiently to properly freeze the hide of an animal, many times depigmentation of the dark hair follicles does not occur.
Ziegler U.S. Pat. No. 3,485,060, granted May 16, 1968 utilizes a liquid cryogenic material to cool a branding tool containing closely spaced highly conductive fingers which directly contact the animal hide. The Ziegler branding iron is not as restricted by the insulating quality of hair on an animal hide as other prior art branding irons. However, the freezing of the hide may only be effected at points on the hide resulting in a "spotty" regrowth of white hair, which is difficult to read.
Although Ziegler further discloses open ducts through the fingers on an alternative embodiment, the ducts only provide a vent for the expanding gases from the vaporizing liquid refrigerant. This escaping gas has the same drawbacks as the Canoy patent and may expose areas of hide not intended to be freeze-branded as it escapes through the finger ducts.